Almost every day we see problems with cars not starting, having a difficult time starting, and the battery light or voltage gauge indicating a problem. Today’s cars have demands on its electrical system that are so far beyond that of 20 years ago. With multiple computers, clocks, radios, DVD players, multiple power outlets, plus many comfort options; most cars should have at least two batteries. The battery and alternator do so much more than start and run the car. So often when a car does not start, the first comment is that the lights turn on and radio works. But that is just the beginning of what the battery does. Much more voltage is required to start a car than ever before.
Stop and think for a moment all that turns on when you start and drive your car. Seasonal issues aside; you have lights, clock, power seats, power mirrors, power windows, electrical door locks, alarm systems, stereos, movie players, GPS systems, phones and laptops charging, and more. In winter there are seat heaters, defrosters and heater system; summer brings air conditioning. Within each of these areas there can be personal amenities that create extra need for voltage and current. Newer cars have multiple computers that require electricity while in use and when car is off to maintain the memories as do stereos and clocks. You may think that batteries and alternators are not as good as in years past when they are actually much better.
Today’s alternator typically have outputs in the 100-150 amp range, where 20 years ago 60-80 amps was the norm, Batteries had 350-400 cranking amp capacities and today most are in the 550-750 range with 1000 amps available. Take a look at the fuse box or boxes on your car and see the range of fuses there. When was the last time you saw a 40 amp fuse much less a 100 amp in a car? Temperatures under the hood are higher and take additional toll on the systems. With all this demand you should have the battery and alternator checked regularly.
What signs should you look for before you have a serious problem? First look for corrosion around the battery posts, corrosion on the cables and into the cable insulation, and the age of the battery. Most OE batteries last about 5 years, replacement 5-7 years. If you see excessive corrosion, that can be a sign of a bad battery or alternator. As the battery starts to breakdown it vents more fumes (acidic) that creates the corrosion you see. This can also be the result of the alternator overcharging the battery or a combination of the two. Keep the connections clean which helps get voltage into and out of the battery. When you have the battery tested, run both a load and circuitry test. A battery can pass one but fail the other; it should pass both. Try to buy the most battery you can afford, but stay within the minimum requirements for your car.
The alternator also has high standards to meet. There is constant demand on the alternator with charging of the battery and running the various equipment of the car. Plus the alternator is a moving part and moving parts do wear and tear. The alternator should meet minimum standards also. Most should operate at about 60% of it new capacity; for example a 100 amp alternator should charge at around 60 amps. Listen for noise from the bearings of the alternator as the engine runs and for headlights to change intensity as engine rpms go up and down. Take a look at the belt that drives the alternator regularly. Low voltage can affect such things as the ABS system, traction systems and other safety related items.
As always have the systems checked annually by your trusted repair shop. A good check should take about 20 minutes, much less time than waiting for a jump.